T173 High-Resolution Investigations of the Permian-Triassic Transition (Posters)

Monday, 23 October 2017
9:00 AM - 6:30 PM
Halls 4EF

CALCISOLS, PALYNOFLORAS, AND RARE CHARCOAL FROM QUAGGASFONTEIN, EASTERN CAPE PROVINCE, SOUTH AFRICA: CORRELATIONS IN THE WAPADSBERG PASS AREA AND IMPLICATIONS FOR LATE PERMIAN CLIMATE

Paper number: T173-2
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

The Karoo Basin, South Africa, is reported to contain a continuous stratigraphic record spanning the terrestrial vertebrate-defined Permian-Triassic boundary (PTB). The current hypothesis links a major biodiversity loss and vertebrate turnover on land to a global change in climate. Rapid climate change has been argued to be evidenced by a changeover from greenish (Permian) to reddish (Triassic) mudrocks, accompanied by a transition in the river architectures from meandering to braided regimes. Here we present results on some other key aspects of this long-standing hypothesis in sections from Quaggasfontein and Piersnaarbakken, northwest of Old Wapadsberg Pass, Eastern Cape Province.

A 70 m detailed section was measured at Quaggasfontein. The stratigraphy differs from those previously reported in the area because of the presence of multiple calcic paleosols containing carbonate cemented nodules beneath the purported PTB. Previous workers have hypothesized that such calcic paleosols formed during the Early Triassic after the extinction event(s). X-Ray fluorescence (XRF) compositional data two Calcisols allows for an evaluation of weathering soil profiles. CIA-K values of these are 60.

A palynological assemblage, characterized by taeniate and alete bisaccates and acavate spores, is recovered from siltstone above the Calcisol horizons. It is comparable to coeval assemblages and represents a glossopterid-dominated woodland with an understory of spore-producing plants. As previously reported elsewhere, a variety of other gymnosperms that are not represented in the autochthonous macrofossil record also are present. Additionally, we report the first occurrence of inertinite from a sandstone body in the section, demonstrating the presence of Fusain in Upper Permian strata of the Karoo Basin.

An 89-meter section measured at Piersnaarbakken, 1.5 km to the north, has been physically correlated with the Quaggasfontein locality. These rocks have been sampled for magnetostratigraphy. To date, we have found a single short reverse polarity chron in a thick section dominated by a normal polarity chron. The magnetostratigraphic record at Piersnaarbakken allows for a temporal understanding of the Quaggasfontein section.

Geological Society of America Abstracts with Programs. Vol. 49, No. 6

doi: 10.1130/abs/2017AM-303520

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